This invention relates to a cup having improved side wall thermal insulation.
Thota U.S. Pat. No. 5,053,594, Atwell U.S. Pat. No. 5,101,084, Atwell U.S. Pat. No. 4,926,020, Wendt U.S. Pat. No. 4,851,631 and Pesheck U.S. Pat. No. 4,988,841 disclose a range of food containers. As shown in these patents, such containers have been provided with a variety of shapes, including side walls which are either smooth or ribbed.
In the past it has been conventional to provide a cup with smooth sidewalls which are covered with a polystyrene foam label. The polystyrene foam label provides thermal insulation that makes it easier to hold the cup when its contents are heated. This approach places considerable demands on the thermal insulation properties of the label, and thereby restricts the materials that are suitable for commercial applications. This can bring disadvantages. For example, the recyclability of a container with a polystyrene foam label may not be optimum in all applications.
Coffee cups are commonly made of paper or plastic foam. Paper cups may not provide adequate insulation to allow a cup of hot coffee to be held comfortably. Plastic foam cups may not provide a suitably hard outer surface for some applications.